This paper seeks to create a hypothesis explaining the transformation of the post-war Japanese state in line with the social changes taking place since 1945. First, considering the reduced significance of theories of the state during the 1970s, I postulate that it was caused by a decline in the violence and centrality of the Japanese state. Second, confirming that in modern nation-states, the monopoly of legitimate violence by the state and national integration based on social and cultural traditions are deeply connected, I show that the post-war Japanese state has been restraining its use of violence in line with the progressive de-traditionalization of the political system. Third, clarifying that theories of the state in the early 1970s presupposed the centrality of the state in spite of the actual decentering of the Japanese state, I find that the position and role of the Japanese state in the high-modern social system can be explained by a pluralistic theory of the state.